Nervous System - Nervous Tissue Flashcards
What are support cells grouped as?
Glial cells or neuroglia
What is the function of support cells? What is the difference between them and neurons?
Support, insulate and protect neurons
Never lose the ability to divide (neurons do which is why nerve damage can be permanent). Also unable to conduct nerve impulses
What are support cells called in the PNS
Schwann and satellite cells
What are support cells called in the rest of the nervous system
- Astrocytes
- Microglia
- Ependymal
- Ogliodendrocytes
- Astrocytes
- brace neurons to blood capillaries
- maintains blood brain barrier
- Microglia
- mobile cells roaming through neural tissue, similar to white blood cells
- monitor health of nearby neurons and dispose of debris (gets rid of dead neurons)
- Ependymal cells
- line cavities of brain and spinal cord
- produce, monitor, and circulate CSF (assisted by cilia)
- Oligodendrocytes
Wrap around nerve fibres in CNS to produce myelin sheaths
Myelinated axons vs unmyelinated axons
Myelinated axons have myelin sheath - regions in CNS with myelinated axons are white matter
Unmyelinated axons are not completely covered by myelin - regions in CNS with cells bodies unmyelinated axons are gray matter
What is myelin sheath?
Protective and insulating layer on axon.
It helps speed up electrical signal transmissions along axon by allowing it to jump from one node to the next. It does this by insulating the axon, which prevents leakage of an electrical impulse
Once damaged, does not regenerate
Schwann cells?
Form myelin sheath in the PNS
What are nodes?
Tiny spaces between unmyelinated parts of axon
What are satellite cells?
Protect neuron cell bodies (not axon)
What are neurons?
Specialized cells that transmit messages from one part of the body to another (messages are called nerve impulses)
They are amiotic (do not reproduce)
Major regions of neurons?
Cell body - nucleus and metabolic centre of cell (all the organelles)
Processes - fibres that extend from cell body (vary in length, up to 4 ft). Include dendrites and axons
Neuron anatomy
Dendrites - receive stimuli from environment or other neurons
Cell body - contains nucleus and other organelles
Axon - carries info away from cell body toward other cells
Axons
Axons continue into axon collaterals or branches, which end in axon terminals
Axon terminals are adjacent to synapse (where neuron communicates with another neuron). Contain vesicle with neurotransmitters that release into synaptic cleft
